Placental issues Flashcards
1
Q
Describe the types of cord insertion (6 types). For each
-Definition
-Incidence
-Risk factors
A
- Velamentous
- cord vessels are separate before insertion
-Incidence 1% - Marginal cord insertion
- cord inserts in or near the margin of the placenta
-7-9%.
-Increased in twin pregnancies. PTL, IUGR, Fetal distress - Succenturiate
- placenta has 1 or more smaller lobe with exposed vessels running between the two
-Incidence - 5%
-Risk factors - Advanced maternal age, IVF, fibroids, Vasa praevia - Bilobate - placenta is bilobed with no exposed vessels between the two lobes. Lobes are roughly the same size.
Incidence - 2-8%
Risks - increase in abruption, polyhydramnios, retained placenta - Circummarginate
-Extrachorial, annular shape with raised edges composed of a double fold or the chorion. Smaller basal plate.
-PPROM, PTB, Placental insufficiency - Circumvallate
-Extrachorional placenta similar to the circummarginate except the transition to the membranous to villous chorion is flat.
2
Q
Discuss fetomaternal haemorrhage
-Definition
-Causes (3)
-Clinical features (5)
-Investigations (3)
A
- Definition
Haemorrhage of fetal cells into maternal circulation - Causes
-Most of the time no cause is found
-Abruption
-Trauma - Clinical features
-Nil
-APH
-Reduced FM
-Symptoms of transfusion reaction in mother is ABO incompatibility
-IUFD - Investigations
-Kleihauer-Bekte test
-MCA PSV >1.3 MoM = moderate anaemia, >1.5 MoM = severe anaemia
-Cord blood haemoglobin (Cordocentesis)
3
Q
Discuss limitations of the kleihauer bekte test.
1. With the test
2. With the results
A
- Limitations with the test
-Manual counting technique
-Technically challenging
-Interobserver variation
-Variable staining which impacts cell counting - Limitations with results
-Is based on an assumption of maternal blood volume so over estimates in small women and under estimates in large women
-Lifespan of fetal RBC are reduced in maternal circulation with ABO incompatibility
-Only 4% of abruptions have +ve kleihauer
-FMH doesn’t equal abruption and vise versa
4
Q
Discuss unexplained APH
-Risks (6)
-Management
A
- Risks
-PTB OR 3.0
-Still birth OR 2.10
-Fetal anomalies OR 1.42
-NICU admission
-Hyperbilirubinemia
-Lower BW - Management
-If spotting only and placenta praevia excluded can be discharged home
-If anything heavier admit for observation at least until stopped
5
Q
Discuss Vasa praevia
-Definition (2)
-Classification (2)
-Risk factors (4)
-Incidence (1)
A
- Definition
-Passage of fetal vessels within free placental membranes within 2 cm of the internal cervical os
-Vessels are not protected by placental tissue or Wharton’s jelly - Classification
Type I - vessel is connected to velamentous umbilical cord
Type II - vessel connects the placenta with a succenturiate or accessory lobe - Risk factors
-Placenta praevia - OR 22
-Bilobed/Succenturiate lobe OR 22
-Velamentous cord insertion - occurs in 2%
-ART OR 8
-LLP in the third trimester - Incidence
-1:2500
6
Q
Discuss diagnosis of vasa praevia
-Screening (5)
-USS features (4)
-Confirmation (2)
A
- Screening
-No evidence to support universal screening
-RANZCOG supports universal screening of cord insertion at mid trimester scan but not routine TVUSS for vasa praevia
-Targeted screening in those with risk factors for vasa praevia with TAUSS then TVUSS if concerning features (RCOG doesn’t recommend - insufficient evidence)
-Need to use colour doppler and TVUSS to confirm. (High sens and spec 100% & 99.8%. Most accurate method RANZCOG)
-Best done 18-20 weeks with confirmation at 30-32 weeks
-If risk factors then consider TVUSS on midtrimester scan - USS features
-Aberrant liner or tubular echolucent structure
-Blood flow within these structures on doppler
-Umbilical artery/venous wave form on pulse doppler
-Aberrant vessel or vessels located within 2cm of internal os attached to the inner perimeter of the fetal membranes - Confirmation
-If seen in 18-20 weeks scan repeat scan at 30-32 weeks
-Resolution occurs in 20%
7
Q
Discuss antenatal management of vasa praevia (11)
A
- Tertiary referral
- Prophylactic hospitalisation from 30-32 weeks (RANZCOG)
- If considering outpatient management a long closed cervix and negative FFN would be reassuring but not evidence based
- Role of cervical length and cerclage is unknown
- Steroids at 32 weeks as precaution for rapid delivery
- Aim delivery 34-36 weeks. Never after 37 weeks
- Immediate CS if PPROM or labour or suspected bleeding from fetal vessels. Have O neg blood available
- If SROM with bleeding and fetal distress consider vasa praevia and deliver. Don’t await Dx
- Aim delivery in a hospital with appropriate neonatal resus ability
- Delivery is by CS with mapping of fetal vessels to avoid laceration
- Send placenta for histo in event of still birth or neonatal death
8
Q
Discuss possible clinical manifestations of vasa praevia (3)
A
- Dx on USS
- Palpation of pulsating fetal vessels at internal os on VE
- Dark red vaginal bleeding and acute fetal compromise after SROM or ARM
9
Q
Discuss management of vasa praevia when undiagnosed on USS (4)
A
- Cat 1 section. Do not wait for diagnosis
- Inform paeds
- Neonatal resus probable
- Neonatal blood transfusion with O neg blood likely
10
Q
What is the fetal prognosis with vasa praevia
-Overall mortality
-Mortality when dx by USS antenatally
-Mortality if undiagnosed antenatally
A
- Overall mortality - 36%
- Mortality with antenatal dx - 3%
- Mortality without antenatal dx 66%
11
Q
Discuss placenta praevia
-Incidence (4)
-Classification (3)
-Risk factors (8)
A
- Incidence
-1:5 at 24 weeks
-1:200 at term
-1:100 if previous CS - RR4.5
-3:100 if 3 previous CS - RR 6.5 - Classification
-Can be assessed if >16 weeks
-Placenta praevia = covering internal os
-Low lying placenta = within 2 cm of internal os - Risk factors
-Smoking OR 1.4
-IVF pregnancy OR 3.7
-Previous D&C
-Previous CS esp if done pre labour or less than 12 months ago. Dose response
-Previous placenta praevia - risk recurrence 4-8%
-Multiparity
-AMA
-Multiple pregnancy
12
Q
Discuss placenta praevia
-Who and when should there be screening (4)
-What are the chances of resolution (2)
-What factors make resolution less likely (3)
-What is the role of cervical length (2)
A
- Who and when should there be screening
-All women should have placental location documented at routine anatomy scan
-Screen if APH
-Repeat scan at 32 weeks as 90% will have resolved
-Repeat scan at 36 weeks as another 50% will have resolved - Factors which make resolution / migration less likely
-Previous CS
-Posterior placenta
-If placenta >2.5cm over internal os - Role of cervical length
-Short cervix (<30mm) <34/40 is predictive of increased risk of haemorrhage and PTB.
-Impact of a cerclage is unknown and not recommended
13
Q
Discuss placenta praevia
-Maternal risks (4)
-Fetal risks (5)
A
- Maternal risks
-PPH
-Hysterectomy
-DIC
-AKI - Fetal risks
-Prematurity and associated perinatal morbidity
-Cord prolapse from malpresentation
-IUGR
-Anaemia from exsanguination if placenta incised during CS
-Fetal mortality - 8:100
14
Q
Discuss presentation of placenta praevia
-Bleeding (6)
-Pain (2)
-Examination (2)
A
- Bleeding
-30% bleed before 30/40
-30% bleed 30-36/40
-30% bleed >36/40
-10% bleed in labour
-Precipitated by shearing forces on placental vasculature - sexual intercourse.
-Often unprovoked - Pain
-Bleeding is usually painless
-Can be associated with contractions either prior to onset of bleeding or post bleeding from uterine irritability - Examination
-Anyone with bleeding and high presenting part need to rule out placenta praevia
-Don’t do a VE
15
Q
Discuss antenatal management of placenta praevia (9)
A
- Optimise Hb
- Ensure up to date G&H with blood put aside if difficult crossmatch
- Advise to avoid sexual intercourse or travel far from medical assistance
- Advise to present if contractions, bleeding, pain
- Consider steroids (RCOG single dose 34-35+6)
- Serial growth scans if APH
- TEDS and mobilisation for thromboprophylaxis
- Individualise location of care based on pregnancy circumstances and social circumstance
- Consent and advise around risk of hysterectomy (2% if praevia, 10% if praevia + prev CS)
- If presenting in PTL with PVB but stable tocolytics can be considered
16
Q
Discuss delivery options for placenta praevia
-Risk factors for emergency caesarian section (4)
-Location (4)
-Mode of delivery (2)
-Timing of delivery (3)
-Preparation of blood products (4)
A
- Risk factors for emergency caesarian section
-Sentinel bleed <29 weeks
-APH esp. if multiple
-Previous CS
-Shortened cervix <3.1cm - Location
-Unit with blood transfusion service and access to critical care
-If CS then should have facilities
-If preterm then should have NICU who can manage that gestation - Mode of delivery
-CS if complete praevia or if heavy or continued bleeding in labour or if maternal or fetal compromise from bleeding
-In LLP VB more likely if: head is engaged and beyond leading edge of placenta, placental edge is <1cm thick. - Timing
-No bleeding 36-37 weeks
-Episode of bleeding 34-36+6 weeks
-Profuse bleeding at any point - Blood product preparation
-2 units id no APH and trialling VB
-4 units if no APH and CS
-6-10 units + FFP if major APH
-Consider cell salvage
17
Q
Discuss delivery of woman with placenta praevia
-Surgical approach (5)
-Methods to manage haemorrhage
A
- Surgical approach
-Consider vertical skin and uterine incision if baby in transverse lie
-Use USS pre and intraoperatively to map placenta boarders
-If placenta is transected clamp umbilical cord immediately
-Have instruments available for hysterectomy
-Have senior obstetrician onsite or scrubbed - Haemostatic techniques
-Close uterus - best way to stop placental bed bleeding unless profuse
-TXA and ecbolics
-Placental bed sutures - 2 x2cm sutures into myometrium
-Uterine artery ligation - dissect bladder down to avoid ureters. Use 1.0 vicryl on blunt needle to ligate. Place suture high and low on either side
-Bakri balloon
-B-Lynch suture- not designed for praevia but can be used in conjunction with balloon. Avoid too tight can cause blanching and necrosis
-Uterine artery embolisation
-Hysterectomy - definitive management
18
Q
Discuss placental abruption
-Definition of abruption (1)
-Incidence (2)
-Risk of recurrence (2)
A
- Definition
-Separation of the placenta from the uterus anytime from viability to second stage of labour - Incidence
-1% of all pregnancies
-50% of cases occur intrapartum - Risk of recurrence
-5% after one abruption
-20-25% after two abruptions
19
Q
Discuss definitions of APH
-Overall definition
-Incidence
-Minor haemorrhage
-Major haemorrhage
-Massive Haemorrhage
A
- Overall definition
-Bleeding from genital tract from 20+0 till birth. No specific amount - Incidence
-3-5% of pregnancies
-20% of very preterm babies born in association with APH - Minor haemorrhage
- < 50mL that has settled - Major haemorrhage
-Blood loss of 50-1000mL with no signs of clinical shock - Massive haemorrhage
-Blood loss >1000mL or signs of clinical shock
20
Q
Discus risk factors of placental abruption
-Incidence of abruption in low risk pregnancies (1)
-Pre-existing factors (4)
-Pregnancy factors (9)
A
- 70% of abruptions occur in low risk pregnancies
- Pre-existing risk factors
-Previous placental abruption OR 7.8 / 5%
-Advance maternal age
-High Parity
-Thrombophillias - FV Leiden and prothrombin gene
-Low maternal BMI - Current pregnancy factors
-IVF
-Bleeding in first trimester esp with haematoma identified
-Trauma - MVA, Domestic violence
-Notching on uterine artery
-PET/HTN
-PPROM, Chorioamnionitis
-SROM with polyhydramnios or multiple pregnancy
-Substance abuse - smoking, cocaine, amphetamines
-ECV
-Non vertex presentation
21
Q
Discuss work up of placental abruption
-Presenting symptoms (5)
-Examination findings (3)
-Investigations (5)
A
- Presenting symptoms
-Abdominal pain - intermittent vs continuous vs absent
-PVB
-Persistent uterine activity or increased tone
-PTL
-Blood stained liquor - Examination findings
-Tender uterus with woody feel and increased tone
-Speculum for source of bleeding and cervical dilation
-Avoid digital exam until praevia excluded - Investigations
-Clinical diagnosis
-CBC and coags
-Kleihauer - Very poor sensitivity and specificity - don’t do as a diagnostic test only use for anti-D guide
-USS - limited diagnostic value. Fails to detect 75% of cases but if reports abruption then there is likely to be an abruption!
-CTG for fetal wellbeing once mother stable
22
Q
Discuss management of placental abruption
-If maternal or fetal compromise (5 points)
A
- ABCD
- Resuscitate mother as first priority
- If fetus is alive aim for delivery
-Instrumental if fully dilated
-CS if not fully dilated
-May need to be under GA if in DIC - If fetus is dead aim for vaginal delivery
-Replace blood and coagulation products - Monitor mother for DIC, AKI, acute anaemia
23
Q
Discuss management of placental abruption
-If NO maternal or fetal compromise in labour (3)
-If NO maternal or fetal compromise not in labour (9)
A
- If in labour
If in labour allow to proceed with continual fetal monitoring
Anticipate PPH as APH risk factor - active third stage
Thromboprophylaxis PN - If not in labour
-Admit and observe 24-48 hrs after bleeding has settled
-Steroids if < 34+6
-Tocolysis is contraindicated but can be considered by senior obstetrician for transfer or steroid completion
-Offer IOL if term.
-Growth scans
-Offer IOL at 37-38 weeks if recurrent bleeding or IUGR otherwise no need for IOL
-Manage anemia
-Give anti-D if required
24
Q
Discuss complications of placental abruption
-Maternal (5)
-Fetal (4)
A
- Maternal
-Anaemia
-Infection
-Hypovolemic shock
-DIC
-PPH - Fetal
-Fetal hypoxia
-SGA and IUGR
-Prematurity
-Still birth
25
Q
Discuss DIC
-Incidence in placental abruption (1)
-Pathophysiology (3)
-Investigations (4)
-Management
A
- Incidence - 35% in placental abruption
- Pathophysiology
-Damaged placental tissue releases thromboplastin triggering extrinsic pathway
-Consumption of clotting factors, platelets and fibrinogen
-Activation of fibrinolytic system resulting in anticoagulation and uncontrolled bleeding
-Micro vascular clot formation can cause end organ damage - Investigations
-APTT, PT, Fibrinogen
-Platelets - Management
-Liaise with senior haematologist
-4 units of FFP and 10 of cryo while waiting for coag studies if relentless bleeding
-Platelets if <50
26
Q
Discuss placenta accreta spectrum
-Pathophysiology of normal placentation (1)
-Pathophysiology of abnormal placentation (3)
A
- Pathophysiology of normal placentation
-Chorionic villi attach to the stratum basalis of the endometrium and are separated from the decidua by the nitabuch line. - Pathophysiology of abnormal placentation
-The Nitabuch line prevents excessive penetration of the decidua by trophoblasts
-In accreta spectrum the layer is absent which stops separation and allows for invasion
-Absence also impacts how the spiral arteries and intervillous spaces develop
27
Q
What are the types of abnormal placentation and what percentage of abnormal placentation to they make up (3)
A
- Placenta accreta
- 80 % of all abnormal placentation
-Chorionic villi attach directly to the uterine myometrium - Placenta increta
-15% of all abnormal placentation
-Chorionic villi invade the myometrium - Placenta percreta
-5% of all abnormal placentation
-Chorionic villi invade through the myometrium and serosa
-May invade adjacent organs that are below the peritoneal reflection (Bowel and bladder)
28
Q
Discuss accreta spectrum disorder
-Incidence (2)
-Risk factors (11)
A
- Incidence
-Rising as increase in CS rates
-1:2000 - Risk factors
-Previous accreta - recurrence rate15-30%
-Scar pregnancy diagnosed in first trimester
-Previous CS: 1 CS OR 2.0; 2 CS OR 9-18; 3 CS OR 56*
-Placenta praevia 3% chance*
-Placenta praevia + CS: 3% if 1 CS, 11% if 2 CS, 40% if 3 CS
-Previous postpartum endometritis
-Previous uterine surgery OR3.4 - MROP, myomectomy, curettage, endometrial ablation
-Short CS pregnancy interval
-Increase in maternal age >35yrs*
-ART
-Abnormally shaped uterus
-Multiparity*
29
Q
Discuss placenta accreta spectrum diagnosis
-Value of antenatal diagnosis (2)
-Who should be screened (1)
-USS utility (2) and findings (8)
-MRI utility (4) and findings (5)
A
- Value of antenatal diagnosis
-50% are not diagnosed antenatally
-Antenatal diagnosis and planning has been shown to reduce morbidity and mortality - Who should be screened
-Women with previous CS and low lying placenta or placenta praevia - USS utility
-Sensitivity 50-70% and specificity 97%. Relies on high clinical suspicion
-Best time to scan 24-26 weeks. Accuracy declines across 3rd trimester - USS findings
-Loss of hypoechoic plane in myometrium underneath the placental bed
-Prescence of numerous lacunae that are large and irregular and contain turbulent flow - “moth eaten ‘
-Loss or interruption of the bright bladder wall
-Thinning of the myometrium overlying the placenta
-Deviation of the uterine serosa away from the expected plane caused by bulge of placental tissue
-Subplacental hypervascularity
-Bridging vessels across myometrium
-Placental lacunae with feeder vessels - MRI utility
-No better than USS but used both together is helpful if placenta posterior
-83% sensitivity, 83% specific
-Scan at 24-28 weeks
-Scan be used to determine extent of invasion esp on posterior placentas - Findings
-Abnormal uterine bulge
-Dark intraplacental bands on T2 weighted
-Heterogenous signal intensity
-Disorganised vasculature of the placenta
-Disruption of the utero-placental sone
30
Q
Discuss risks of placenta accreta spectrum for mothers (6)
A
- Haemorrhage - 50% have PPH
-Medium blood loss 2-8L
-Massive transfusion >10 units in 40% - Hysterectomy
- Bladder injury - 17%
- Ureteric injury - 10-15%
- Mortality - 6%
- Uterine rupture at any time in pregnancy esp if percreta
31
Q
Discuss antenatal management of placenta accreta spectrum
-Who should be involved (7)
-Where should delivery occur (4)
-Timing of delivery (2)
-Bleeding considerations (3)
-Surgical planning (3)
A
- Who should be involved
-MDT input from obs, gynae, urologist, radiologist, haematologist, anaesthetist, vascular - Location of delivery
Plan delivery at location with high volume transfusion capability, surgical specialties, ICU, NICU - Timing of delivery
-Aim 35-36+6
-If APH or risks factors for preterm delivery consider after 34/40 - Bleeding considerations
-Valid G&H
-Optimise Hb
-Consider cell salvage - Surgical planning
-Consider MRI for surgical planning
-Anaesthetic review
-Counsel woman regarding surgical risks and options for surgery
32
Q
Discuss delivery for placenta accreta spectrum
-Bleeding considerations (4)
-Anaesthetic type (2)
-Positioning (1)
-Incision type (3)
-Ecbolics (2)
-Urological considerations (3)
-IR considerations (4)
A
- Bleeding considerations
-Alert blood bank
-Cross match 4 units initially
-Alert haematologist and have available
-Consider access to cell saver - Anaesthetic type
-Both regional and GA
-Choice to be made in conjunction with woman - Positioning
-Lithotomy to allow access from between leg and to access vagina and do cystoscopy if required - Incision type
-Midline on skin
-USS to map placenta and cut away from this
-Consider fundal or high transverse incision - Ecbolics
-Don’t give if planning to leave placenta insitu
-Can use if planning to take placenta out - Urological considerations
-Urological stents no routinely required but if bladder invasion suspected can use
-Consider early cystotomy at site of placental invasion and bladder repair instead of dissection - IR considerations
-Preoperative balloon placement is controversial. No good RCT evidence. Not routinely recommended
-Consider balloon placement in those where hysterectomy is planned
-Uterine artery embolisation in women who are attempting to preserve the uterus can be considered if PPH
-Balloon complications include internal iliac artery dissection
33
Q
Discuss surgical options for managing placenta accreta spectrum
-Considerations for surgical options (6)
A
- Things to consider regarding surgical options
-Position of placenta
-Depth of invasion
-Parametrial extension
-Visual inspection at the time
-Presenting clinical symptoms
-Woman’s preferences
34
Q
Discuss surgical options for managing placenta accreta spectrum
-Attempted delivery of placenta (5)
A
-Consider if depth and surface area of placenta is limited
-High risk for significant bleeding
-Manage as placenta praevia with ecbolics, placental bed sutures, b-lynch, uterine artery ligation and Bakri balloon
-May require partial myomectomy at placental site and then repair of uterus
-Early recourse to hysterectomy if bleeding ongoing
35
Q
Discuss surgical options for managing placenta accreta spectrum: Leave placenta insitu
-Considerations (2)
-Surgical approach (3)
-Possible outcomes (3)
-Risks of retained placenta (9)
-Clinical follow-up (4)
A
- Considerations
-Consider if undiagnosed and in location without appropriate services to enable transfer or if hysterectomy considered inappropriate to team or woman
-Consider in appropriately counselled women who will be able to commit to long term FU - Surgical approach
-Deliver baby via uterine incision well away from placenta.
-Trim and tie cord close to placental insertion site.
-Do not give ecbolics - Possible outcomes
-40% need hysterectomy for uncontrolled bleeding
-Resorption occurs over 14 weeks
-Some pass the placenta - Risk of leaving placenta
-40% severe morbidity
-Chronic bleeding
-Sepsis
-Peritonitis
-Uterine necrosis
-Fistula
-Injury to adjacent organs, AKI, pulmonary oedema
-DVT/PE - Clinical follow-up
-Regular clinical review
-Serial HCG
-No evidence methotrexate as adjuvant therapy
-Prophylactic antibiotics
-Repeat placenta accreta up to 30%. Good fertility rates
36
Q
Discuss surgical options for managing placenta accreta spectrum
-Planned CS hysterectomy (4 points)
A
- Best practice as reduced risk of massive haemorrhage - contraversial. Observational studies suggest less blood loss with conservative measures
- Delivery baby through uterine incision distant to placenta
- Close uterus then undertake hysterectomy enbloc
- Cystomoy is OK
37
Q
What is the triple P procedure for managing placenta accreta spectrum
A
- Perioperative location of placenta and delivery fetus from incision above the upper boarder
- Pelvic devascularisation with IR placed occlusion balloons in both illiac arteries
- Placental non-separation with myomectomy excision and reconstruction of uterine wall
38
Q
Discuss antepartum haemorrhage
-Definition (1)
-Incidence (2)
-Most important causes (2)
A
- Definition
-Any bleeding from genital tract from 24/40 until delivery - Incidence
-Complicates 3-5% of pregnancies
-Leading cause of maternal and fetal mortality - Most important causes
-Abruption
-Praevia
39
Q
Discuss complications of APH
-Maternal (9)
-Fetal (5)
A
- Maternal complications
-Anaemia
-Infection
-Maternal shock
-Renal tubular necrosis
-Consumptive coagulopathy
-PPH
-Psychological sequalae
-Complications of blood transfusion - Fetal complications
-Fetal hypoxia
-SGA or IUGR
-Prematurity
-Mortality
-NICU admission and hyperbilirubinemia
